1. Field of the Invention
The present invention relates to an optical disc recording and playback apparatus that is configured so as to record signals onto a disc by a laser emitted from an optical pickup and to perform playback of the signals that have been recorded on the disc by the laser.
2. Description of the Related Art
Disc players for performing operations to read signals that have been recorded on a disc using an optical pickup are popular. However, in addition to the playback function, optical disc recording and playback apparatuses, which are configured to enable the recording of signals to discs by a laser emitted from the optical pickup, have recently been manufactured on a commercial basis.
Furthermore, optical disc recording and playback apparatuses have recently been developed to enable the recording of signals in a state controlling the rotation of the disc at fast constant linear velocities, such as 4X, 8X, 12X, and 16X with respect to a standard recording linear velocity.
More recently, amidst the demand for faster recording speeds, a technique called zone CLV has been developed. Since the rotational speed of a spindle motor becomes extremely fast when the recording linear velocity is increased at the inside of the disc, this technique performs the recording operation at a low constant linear velocity at the inside of the disc, and changes the linear velocity to a faster velocity when the recording position moves toward the outside of the disc.
The optical disc recording and playback apparatus is configured to perform the recording operation of signals according to a record command from a host. This recording operation first stores the signal, which is to be recorded onto the disc, into a buffer RAM, then records the signal onto the disc by reading out the signal that is stored in the buffer RAM. A recent development is an optical disc recording and playback apparatus that is capable of resuming the recording operation from a position at which the recording was interrupted, such as due to the apparatus receiving an impact during the recording operation.
When the optical disc recording and playback operation receives an impact during a recording operation, the tracking servo signal and the focus servo signal for performing control operations of the optical pickup are greatly disrupted. For this reason, the apparatus is configured to perform a control operation when the recording is interrupted by detecting whether or not the level of the changing servo signal at this time exceeds an error detection level.